JP7746329B2 - Connection Unit - Google Patents

Description

The present invention relates to a connection unit for connecting a power supply line to an exhaust gas heater in an exhaust gas system for an internal combustion engine.

It is known to use exhaust gas heaters that generate heat by electrical excitation to supply heat to the exhaust gases flowing in the exhaust gas system of an internal combustion engine, particularly during the start of operation of the internal combustion engine, in order to more quickly heat an exhaust gas treatment unit, such as a catalytic converter or particulate filter, arranged in the exhaust gas system, thereby bringing the exhaust gas treatment unit to operating temperature more quickly. The heat is absorbed by the exhaust gases flowing through such an exhaust gas heater and can be transferred to the downstream exhaust gas treatment unit. To electrically excite such an exhaust gas heater, it is necessary to apply a voltage provided by the vehicle electrical system to the heating area of the exhaust gas heater using a connection unit that runs electrically insulated through the exhaust gas system components that contain the exhaust gas heater and guide the exhaust gas.

The object of the present invention is to provide a connection unit for connecting a power supply line to an exhaust gas heater of an exhaust gas system of an internal combustion engine, which is simply constructed, resistant to thermal overloads, and configured to accept large currents.

According to the invention, the object is to provide a connection unit for connecting a power supply line to an exhaust gas heater of an exhaust gas system of an internal combustion engine, the connection unit comprising:
a connecting element comprising an electrically conductive connecting element body elongated in the direction of its longitudinal axis, the connecting element having an exhaust gas heater connection region in a first axial end region and a power supply line connection region in a second axial end region, the power supply line connection region comprising an end of the connecting element body and a radial protrusion of the connecting element body continuing from the end;
a support element for fastening the connection unit to an exhaust gas system component, the support element having a support element opening pierced by a connection element body at a radial distance relative to the support element;
The problem is solved by a connection unit comprising: a support unit for supporting a connecting element on a support element in axial and radial directions, the support unit comprising: a first support element made of an electrically insulating material supported on the support element in a first axial direction and radially outward and supported in a second axial direction opposite to the first axial direction with respect to the radial protrusion; and a second support element made of an electrically insulating material supported on the support element in the second axial direction and radially outward.

In a connection unit constructed according to the present invention, the radial protrusions on the connection element body can be used for a dual function: as a receptacle for gas-tight and electrically insulated support of the connection element on the support element, and, in the power supply line connection area, as a receptacle for the power supply line to be connected to the connection unit. This results in a simple yet functionally reliable structure. It also provides a simple possibility for disconnecting the power supply line from the connection unit if necessary.

For a particularly simple and stable construction, the radial protrusions may form an integral part of the connecting element body. This means that the radial protrusions are formed integrally with the connecting element body, i.e. as a material block, and provide the connecting element.

To avoid areas in the connecting element body that are subject to high thermal and/or mechanical stress, it is proposed that the connecting element body be formed substantially cylindrical. This allows the connecting element body to be formed with a substantially constant, large diameter over its entire length. Changes in radial dimension are then only present in the area of the radial projections.

In order to ensure a defined positioning of the connecting element when the power supply line is attached, it is proposed that a tool action structure be formed on the outer peripheral region of the radial protrusion. For example, the tool action structure may comprise two substantially parallel outer peripheral surface portions of the outer peripheral surface of the radial protrusion, which allows the connecting element to be fixed against rotation by means of pliers or a wrench during the attachment or removal process of the power supply line.

For fastening the power supply line to the power supply line connection area, for example by means of a nut, the end may be formed with a substantially cylindrical outer circumferential contour and/or may be provided with an external thread.

For a defined support interaction between the support element and the support element of the support unit, a first support component may be formed on a first axial side of the support element for axially and radially supporting the first support element, and a second support component may be formed on a second axial side of the support element for axially and radially supporting the second support element.

To achieve a defined positioning of the support element in the axial and radial directions, and in particular to achieve a gas-tight connection of the support element to the support element, it may be specified that the first support component comprises a first support notch defined in a first axial direction by a first notch bottom and radially outwardly defined by a first notch wall, and/or the second support component comprises a second support notch defined in a second axial direction by a second notch bottom and radially outwardly defined by a second notch wall.

The support element may be made of a metallic material so that it can be fixed to the exhaust system component, for example by welding.

In order to ensure sufficient electrical insulation even when relatively large currents flow through the connection elements, it is proposed that the first support element and/or the second support element be made of a ceramic material.

Due to the defined radial centering of the connecting element relative to the support element, the connecting element may pass through the first support element opening of the first support element substantially without radial movement play and/or pass through the second support element opening of the second support element substantially without radial movement play.

In order to avoid excessive mechanical stresses, particularly during thermal loading of the connecting element, it is proposed that the radial protrusion be supported in the first axial direction relative to the first support element by means of an axially elastic preload unit.

For example, the preload unit may include at least one preload spring, preferably a disc spring.

Local mechanical overloading of the first support element by the preload unit can be avoided, for example, by supporting at least one preload spring in the first axial direction on the first support element by means of a first disk-shaped transmission element. This first disk-shaped transmission element may, for example, be made of a metallic material.

The connecting element may be supported in the second axial direction on the second support element by means of a second disk-shaped transmission element, for example made of a metallic material.

In such a configuration, the second transmission element may be fixed to the connecting element body by a material connection, preferably by welding, to obtain a rigid connection.

The present invention further relates to an exhaust gas system for an internal combustion engine, comprising an exhaust gas system component for guiding exhaust gases, at least one exhaust gas heater arranged in the exhaust gas system component, and at least one exhaust gas treatment unit downstream of the at least one exhaust gas heater, and in which at least one connection unit assigned to the at least one exhaust gas heater and configured according to the present invention is fixed to the exhaust gas system component.

The present invention will now be described in detail with reference to the accompanying drawings.

1 is a side view showing a connection unit for connecting a power supply line to an exhaust gas heater of an exhaust gas system. FIG. 2 is an axial view of the connection unit of FIG. 1 as seen in the viewing direction II shown in FIG. 1; 3 is a longitudinal cross-sectional view of the connection unit taken along line III-III shown in FIG. 2. FIG. FIG. 1 is a principle diagram showing an exhaust gas device for an internal combustion engine.

Before describing in detail the structure of a connection unit for connecting a power supply line to an exhaust gas heater of an exhaust gas system with reference to Figures 1 to 4, the basic structure of such an exhaust gas system, for example of an internal combustion engine in a motor vehicle, will be described with reference to Figure 5.

The exhaust gas system 10 includes an exhaust gas system component 12, which may be configured, for example, as a tube or housing, through which exhaust gas A discharged from an internal combustion engine flows. An exhaust gas treatment unit, generally designated 14, is located within the exhaust gas system 12. This exhaust gas treatment unit 14 may be configured, for example, as a catalytic converter, such as an oxidation or SCR catalytic converter, a particulate filter, or the like. An exhaust gas heater 16 is arranged upstream of the exhaust gas treatment unit 14. The exhaust gas heater 16 includes a heating area, for example, configured with a heating conductor, through which the exhaust gas A flows. The exhaust gas A absorbs heat and transfers it to the downstream exhaust gas treatment unit 14. This ensures faster heating of the exhaust gas treatment unit 14, particularly during operating phases when the exhaust gas A discharged from the internal combustion engine is still relatively cold or when the exhaust gas treatment unit 14 has not yet reached the operating temperature required for catalytic reactions.

To apply a voltage to the exhaust gas heater 16, which is used to heat the heating area of the exhaust gas heater 16, a connection unit, generally designated 18, is used for connection to each pole of the vehicle electrical system. A power supply line of the vehicle electrical system can be connected to each connection unit 18, so that the application of a voltage to the exhaust gas heater 16 and the resulting current flow through the exhaust gas heater 16 can heat the exhaust gas A or other gases guided through the exhaust gas system component 12.

The connection unit 18, shown in detail in Figures 1 to 4, comprises a pin-shaped connection element 20 as its central component. The connection element 20, made of a metallic material, comprises a connection element body 22 having an essentially cylindrical structure elongated in the direction of the longitudinal axis L, which means that the connection element body 22 has substantially the same radial dimensions or cross-sectional geometry in all axial regions relative to the longitudinal axis L.

At a first axial end region 24, which is to be positioned inside the exhaust system component 12, the connection element 20 has an exhaust heater connection region 26, where the connection element 20 or the connection element body 22 is electrically conductively connected to a heating region 30 of the exhaust system component 16, for example by a weld 28. At a second axial end region 32, which is to be positioned outside the exhaust system component 12, the connection element 20 has a power supply line connection region 34, where the connection element 20 is or can be connected to a power supply line, generally designated 36, as will be described below.

The power supply line connection region 34 comprises an end 38 of the connection element body 22 and a radial protrusion 40, contiguous with the end 38 and preferably completely surrounding the longitudinal axis L. The radial protrusion 40, which is formed integrally with the connection element body 22, i.e., as a block of material, provides a planar bearing surface 42, substantially perpendicular to the longitudinal axis L, for the power supply line 36 or a cable shoe 44 or the like provided on the power supply line 36.

The end 38 of the connection element body 22 is provided with an external thread 46, which allows a nut 48 to be threaded onto this end 38, thereby immovably fixing the power supply line 36, e.g., a cable shoe 44, to the power supply line connection area 34 of the connection element 20.

To this end, as can be seen in FIG. 2 , the radial protrusion 40 is provided with a tool action arrangement 50, which may comprise, for example, substantially parallel outer peripheral surface portions 52, 54 of the outer peripheral surface 56 of the radial protrusion 40 in two diametrically opposite regions of the radial protrusion relative to the longitudinal axis L. This allows the nut 48 to be screwed in using a tool, such as a wrench, pliers, or the like, when fastening the power supply line 36 to the power supply line connection region 34, and further allows the tool to be applied to the radial protrusion 40, which prevents the connecting element 20 from rotating together with the nut 48 and thus ensures that the nut 48 can be screwed in with a specified tightening torque.

Therefore, due to the substantially cylindrical shape of the connection element body 22 even in the region of the end 38, it is easy to release the power supply line 36 or its cable shoe 40 for disconnecting or replacing it by removing the nut 48, and then pull the cable shoe 40 axially away from the end 38 without having to overcome the clamping force. This facilitates installation and removal of the power supply line 36, particularly in areas of the vehicle or exhaust system 10 that are difficult to access. At the same time, the radial protrusions 40 provide a relatively large outer surface in the form of cooling ribs, which makes it possible to avoid local overheating due to heating caused by exhaust gases flowing around the exhaust gas heater connection region 26 or by relatively large currents flowing through the connection element 20.

To secure the connection unit 18 to the exhaust system component 12, the connection unit 18 includes an annular support element 58 made of a metallic material. The exhaust system component 20 has an exhaust system component opening 60 associated with the support element 58, into which the support element 58 can be positioned for engagement. For this purpose, a centering notch 62 may be formed in the outer circumferential region of the support element 58. The support element 58 can be secured to the exhaust system component 12 by a weld 64, e.g., a weld seam that completely surrounds the longitudinal axis L, thereby providing a gas-tight connection in the adjoining region of the support element 58 with the exhaust system component 12.

For the defined, electrically insulated holding of the connecting element 20 on the support element 58, a support unit, designated as 66 in its entirety, is provided. This support unit 66 comprises an annular, disk-shaped first support element 68, by means of which the connecting element 20 is supported on the support element 58 in the first axial direction _R1 . Assigned to the first support element 68, the support element 58 has, on one axial side thereof, a first support formation 69 with a first support notch 74, which is defined in the first axial direction _R1 and radially outward by a first notch bottom 70 and a first notch wall 72. In the first support notch 74, the first support element 68 is held radially centered, with substantially no radial movement play between the first support element 68 and the first notch wall 72, which preferably completely surrounds the longitudinal axis L in the circumferential direction. The substantially planar abutment of the first support element 68 on the first cutout bottom 70 and the substantially radial play-free abutment of the first support element 68 on the first cutout wall 72 provide a labyrinth-like sealing interaction between the support element 58 and the first support element 68. Additionally, a heat-resistant, e.g., disk-shaped, sealing element can be arranged, for example, between the first support element 68 and the first cutout bottom 70.

The first support element 68 further has a first support element opening 75 through which the connection element body 22 of the connection element 20 is guided substantially without radial play. This allows the first support element 68 to determine a specific radial positioning of the connection element 20 relative to the support element 58. This ensures that the connection element body 22 passes substantially centered through the support element opening 76 formed in the support element 58, so that there is no contact between the connection element 20 and the support element 58.

The support unit 66 comprises a second support element 78, which is likewise formed in the shape of an annular disk. Assigned to the second support element 78 and on the other axial side of the support element 58 facing the exhaust system component 12, a second support formation 79 is provided which comprises a support recess 84 which is delimited by a second recess bottom 80 and a second recess wall 82 in a second axial direction _R2 and radially outward relative to the longitudinal axis L. As a result, the second support element 78, which is received in the second support recess 84, supported axially in the second axial direction _R2 , and continues radially outwardly into the second recess wall 82 substantially without movement play, is supported on the support element 58 at a defined axial and radial position, and the second support element opening 86 of the second support element 78, which is pierced substantially without movement play by the connecting element body 22, serves for further defined positioning of the connecting element 20 in the support element opening 76. Furthermore, the interaction between the second support element 78 and the second support recess 84 forms another sealing arrangement acting in the manner of a labyrinth, thereby ensuring a further improved gas-tight connection to the connection unit 18. A sealing element, for example in the form of a disk, may also be arranged between the second support element 78 and the second recess bottom 80.

For axially supporting the connecting element 20 in the first axial direction _R1 on the support element 58 via the first support element 68, the support unit 66 further comprises a preload unit, generally designated 88. In the illustrated embodiment, the preload unit 88 comprises two oppositely arranged disc springs 90, 92. The disc spring 90 is supported in its outer peripheral region on the radial projection 40, and the disc spring 92 is supported in its outer peripheral region on the first support element 68 via an annular disk-shaped transmission element 94. The two disc springs 90, 92 support each other in their radially inner region.

To axially support the connecting element 20 in the second axial direction _R2 relative to the support element 58, a second annular disk-shaped transmission element 96 is provided adjacent to the second support element 78, which, like the first annular disk-shaped transmission element 94, may be made of a metallic material. The second annular disk-shaped transmission element 96 is fixed to the connecting element body 22 by a weld 98, so that the two support elements 68, 78, the two disc springs 90, 92, and the first transmission element 94 are axially preloaded and held between the radial projection 40 and the second transmission element 96 by the preloading action of the preloading unit 88. Due to this preloading action, the two support elements 68, 78 are also held immobile in the support recesses 74, 84 assigned to them. The essentially axially elastic mounting of the connecting element 20 within the support element 58 by the action of the preload unit 88 avoids the occurrence of excessive stresses that may occur, for example, due to thermally induced length changes, particularly of the connecting element 20.

The above-described structure of the connection unit 18 combines various particularly advantageous features. For example, it allows the power supply line 36 to be easily and precisely fastened to the power supply line connection area 34 with a defined fastening torque, or to be removed from the power supply line connection area 34 without having to overcome any friction or clamping torque. Due to the relatively large, constant cross-section of the connection element body 22, the connection element body 22 is also suitable for receiving relatively large currents. Due to the radial projections 40 and the cooling effect they provide, excessive heating in the region of the connection unit 18 is avoided, even when heated by exhaust gas A or current conducted through the connection element 20. Overloads resulting from thermally induced length changes are also avoided, since these length changes can be compensated for in the preload unit 88, which also ensures that the two support elements 68, 78 are pressed against the support element 58 with a substantially constant pressing force. This ensures a sealing interaction between the support elements 68, 78 and the support element 58 that is not affected by changes in the length of the connection element 20. At the same time, the support elements 68, 78, which are made of an electrically insulating material, such as a ceramic material such as aluminum oxide or magnesium oxide, provide sufficient electrical insulation between the connection element 20 and the support element 58, even in view of large currents.

Claims (19)

A connection unit for connecting a power supply line to an exhaust gas heater of an exhaust gas system of an internal combustion engine,
a connection element (20) having an electrically conductive connection element body (22) elongated in the direction of a longitudinal axis (L), the connection element having an exhaust gas heater connection area (26) in a first axial end region (24) and a power supply line connection area (34) in a second axial end region (32), the power supply line connection area (34) comprising an end portion (38) of the connection element body (22) and a radial protrusion (40) of the connection element body (22) continuing from the end portion (38), the radial protrusion (40) forming an integral part of the connection element body (22);
a support element (58) for fixing the connection unit to an exhaust gas system component (12), the support element (58) having a support element opening (76) penetrated by the connection element body (22) at a radial distance relative to the support element (58);
a support unit (66) for supporting the connection element (20) on the support element (58) in the axial and radial directions, the support unit (66) comprising: a first support element ( ₆₈ ) made of an electrically insulating material supported on the support element (58) in a first axial direction (R1) toward the first axial end region (24) of the connection element ( ₂₀ ) and radially outward; and a second support element (78) made of an electrically insulating material supported on the support element ( ₅₈ ) in the second axial direction (R2) and radially outward, the second support element (68) being supported on the support element (58) in a second axial direction (R2) opposite to _the first axial direction (R1) with respect to the radial protrusion (40) and toward the second axial end region (32) of the connection element (20). A connection unit as described in claim 1, characterized in that the connection element body (22) is formed substantially cylindrically. A connection unit according to claim 1 or 2, characterized in that a tool action component (50) is formed in the outer peripheral region of the radial protrusion (40). A connection unit as described in claim 3, characterized in that the tool action component (50) comprises two substantially parallel outer peripheral surface portions (52, 54) of the outer peripheral surface (56) of the radial protrusion (40). A connection unit according to claim 1 or 2, characterized in that the end (38) is formed with a substantially cylindrical outer peripheral contour and/or the end (38) is formed with an external thread (46). A connection unit according to claim 1 or 2, characterized in that a first support component (69) for supporting the first support element (68) in the axial and radial directions is formed on a first axial side of the support element (58), and a second support component (79) for supporting the second support element (78) in the axial and radial directions is formed on a second axial side of the support element (58). 7. A connection unit according to claim 6, characterized in that the first support component (69) comprises a first support notch (74) defined in the first axial direction (R ₁ ) by a first notch bottom (70) and radially outwardly defined by a first notch wall (72), and/or the second support component (79) comprises a second support notch (84) defined in the second axial direction (R ₂ ) by a second notch bottom (80) and radially outwardly defined by a second notch wall (82). A connection unit according to claim 1 or 2, characterized in that the support element (58) is made of a metal material. A connection unit according to claim 1 or 2, characterized in that the first support element (68) is made of a ceramic material, and/or the second support element (78) is made of a ceramic material, and/or the connecting element (20) passes through the first support element opening (75) of the first support element (68) with substantially no radial movement play, and/or passes through the second support element opening (86) of the second support element (78) with substantially no radial movement play. 3. A connection unit according to claim 1 or 2, characterized in that the radial projection (40) is supported in the first axial direction ( _R1 ) relative to the first support element (68) by means of an axially elastic preload unit (88). A connection unit as described in claim 10, characterized in that the preload unit (88) comprises at least one preload spring. The connection unit of claim 11, wherein the at least one preload spring comprises a disc spring (90, 92). 12. A connection unit according to claim 11, characterized in that said at least one preload spring is supported in said first axial direction ( _R1 ) on said first support element (68) by means of a disk-shaped first transmission element ( 94 ). A connection unit according to claim 13, characterized in that the disk-shaped first transmission element (94) is made of a metallic material. 3. A connection unit according to claim 1 or 2, characterized in that the connection element (20) is supported in the second axial direction ( _R2 ) on the second support element (78) by means of a disk-shaped second transmission element (96). A connection unit as claimed in claim 15, characterized in that the disk-shaped second transmission element (96) is made of a metallic material. 16. A connection unit according to claim 15 , characterized in that the second transmission element (96) is fixed to the connection element body by a material connection. A connection unit as described in claim 17, characterized in that the second transmission element (96) is fixed to the connection element body by welding. An exhaust gas system for an internal combustion engine, comprising an exhaust gas system component (12) for guiding exhaust gas (A), at least one exhaust gas heater (16) arranged in the exhaust gas system component (12), and at least one exhaust gas treatment unit (14) downstream of the at least one exhaust gas heater (16), wherein a connection unit according to claim 1 or 2 is fixed to the exhaust gas system component (12) and assigned to the at least one exhaust gas heater (16).